Wooden beam constructions



May 19 1959 K. H. BRosENlus 2,886,857

WOODEN BEAM ooNsTRucToNs Filed Dec. 14, 1953 '7 Sheets-Sheet 1 FQ- 1 i wFig. 2

\f 759/ A( Y X\ 3 Fig. 3

INVENTOR Karl Milling Braseums B May 19, 1959 K. H. BRosENlus 2,886,857

` WOODEN BEAM coNsTRucToNs Filed Dec. 14, 1955 rz sheets-sheet 2fr/vEA/Tan Karl Hila x3 Brusema s By/IJWMAI ATToRA/Y May l19, 1959 K. H.BRosENlus 2,886,857

Y WOODEN BEAM CONSTRUCTIONS Filed Dec. 14. 1953 `'7 Sheets-Sheet 3 s fmm A "\2& w y gf XYYWw,

INVENTO Karl Hildn grose'nius ATTORNY K. H. BROSENIUS WOODEN BEAMCONSTRUCTIONS May 19, 1959 '7 Sheets-Sheds 4 Filed Dec .I 14,` 1953 Fig.17

INVENTOR Karl Hlalw Broscmvus By M May 19, 1959 K. H. BRosl-:Nlus2,886,857

WOODEN BEAM coNsTRUcTroNs Filed Dec. 14, 1955 fr sheets-sheet 5 Fig. 2O

INVENTDF? Karl H (ldv Brosev v5 By ATTom/v MayV 19, 1959 K. H: BRosENlUs2,886,857

" WOODEN BEAM coNsTRUcToNs Filed Dec. 14, 1953 7 Sheets-Sheet 6 K. H.BRosENlUs 2,886,857

WOODEN BEAM coNsTRucTloNs '7 Sheets-Sheet 7 "May 19, 1959 Filed Dec. 14,1955 Iwan-ron 'Karl Hhln Bruszmur 5%,

` ATToRNEY altem:

2,886,857 Patented May i9, 1959 hice WOODEN BEAM CONSTRUCTIONS KarlHilding Brosenins, Stockholm, Sweden, assigner to HyresgasternasSparkasse-och Byggnadsforeningars gikscorbund, Stockholm, Sweden, anassociation of we en Application December 14, 1953, Serial No. 398,150

4 Claims. (Cl.'20.5)

This invention relates to certain constructions of wooden beams whichconsist of a web of boards crossing each other diagonally and woodenflange laths or strips or frame-bars attached at theedges of this web bynailing.

According to a well-known construction said flange laths consist ofordinary solid timber which is normally to be had on the market inrelatively restricted lengths. When using ordinary nails with relativelyclose nailing, which is often necessary for heavily loaded beams of thetype now referred to, there is often the risk of splitting being causedin the rows of nails in the above-mentioned laths, resulting in aconsiderable reduction of the strength of the beam. This risk isparticularly incurred since `in Abeams of greater length the flangelathsmust be lengthened by `joining further pieces of lath by means ofnailing while using joint-pieces externally of the joint. In this caseparticularly close nailing and consequently long, and, as a rule alsoheavy nails or spikes are required.

The main object of the present invention is to eliminate the saiddrawback by providing means for making large and strong beams in a mostsimple manner, while at the same time avoiding overlapping unattractivejoints for the ange-laths. The invention relates to the type of beams inwhich each flange is composed of two or more layers of boards (forexample of about 1" thickness), which are glued together along verticalplanes and in which `these anges are arranged in pairs on both sides of`a web cornposed of at least two layers of boards crossing each otherdiagonally. According to one feature of the invention the flanges areattached to this web by means of wirenails, the diameter or edgeside ofwhich is small in relation to the length of the nails as compared withnails now in use for corresponding purpose. Preferably, the thickness ofthe nails does not exceed about Hgo or in extreme cases 1/5 of thelength of the nails. The maximum diameter of the nail is for instance0.25 to 0.30.

The boards in each layer of boards of the llanges are jointedlongitudinally by means of glued oblique joints, hook joints, ngerjoints or such like. These joints are so arranged in the longitudinaldirection of the anges in relation to the joints in adjoining layers ofboards that all joints in a flange will be distributed with approximateuniformity in the longitudinal direction of the flange. Also the nailsby means of which the flanges are attached to the web of the beam aredistributed substantially `uni- 'formly inthe longitudinal direction ofthe flange. `In this manner the nails will function as joint-nailing by`successive transmission of load, and thus they will also serve as anadditional safety factor for the individual layersof boards of theflanges, should the gluing between said layers or between the jointsfail to function. Finally, the nails will also act to transfer allstresses appearing between the flanges and the web and between the webboards.V

When timber of limited splitting resistance is used, beams with nailedlianges according tothe invention have practically no disposition tosplit even with relatively close nailing of the flanges. `They can`therefore be loaded so as to take full advantage of `thestrength ofthe` Wooden material used. This is due to a cooperation 'of severalcircumstances. In `the first place theactual flanges acquire inthemselves aconsiderable splittingresistance by gluing together severaldifferent layers of boards to one another as the fibres in the differentlayers of boards .are never completely parallel but cross one another ata certain angle so that when they are glued they will block one anothersbres. The flanges thus acquire a consider'A ably greater strength andsplitting resistan-ce than ordinary tirnber. Secondly, also the webboards extending-at aniangle to the flanges will contribute to anincreased splitting resistance of the flanges. The parts of the weblying between the opposite pairs of flanges are not, however, blocked inthe same way as the flanges by combining several layers. Splitting ofthe web boards can,however, according to the invention, be otherwisecounteracted, namely by carefully arranging the boards of the diagonalpanelling layers close together without any intervening space betweenthe individual boards, whereupon nailing is effected right through theflange on one side of the web, then through both the diagonal panellinglayers and, finally, into the flange on the other side of the web. Theflanges extending in the longitudinal direction of the beam whichareglued together by vertical layers of board, will in this way block theboards of the diagonal panelling which are laid close together and thusprevent splitting also in the web boards.

The nails which are thin relative to the length thereof and which areused for the flanges Yalso result ina remarkable increase in thesplitting .resistance of those wooden sections which are nailed `throughto resist splitting, or vice versa, a considerable increase in thepossibilities of performing close nailing will be obtained. This in turnrepresents a corresponding increase in the bearing capacity and strengthof the beam.

Ordinary wire nails of round sectionare usually characterized by thecross dimension increasing with the length of nail, and this cross sizeis so great with the nail lengths which are suitable for nailing theflanges: that the 'nail is very apt, especially with hard and strongkinds of woods, to cause splitting when `thenailing is close. By way ofexample, the ordinary round wire nail with a length of'6 has a crossdimension of 0.26, and `8 round ordinary wire nails have a cross size of0.33, whereas for nailed beams according to the invention the mostsuitablecross dimension for 6" nails is only about 0.20'Hand thecorresponding cross size for 8" nails is about 0.24. I have found thatthe latter size should not be `increasedmaterially even if still longernails than 8 be used. If the beam flanges are connected to lthe web withthese nails which are thin in proportion to their length, I have foundthat the risk of splitting is reduced and the bearing capacity increasedto a very high degree. In additionl have found that by using nails ofone andthe same quantity by weight, and consequently nails of one andthe same cost, the bearing capacity of the nailed assembly increases,irrespective of the risk of splitting, according as the cross dimensionof the nail decreases. The nailing according to the invention, withspecially thin nails in relation to the length of nail, thereforeentails decided advantages from several points of View.

One object of the invention is also to provide afurther improvement ofthe splitting resisting propertyof `the through-nailed beam portionsbyarranging the nailing `according Vto `a predetermined pattern. In thisembodiment the nailing between flanges and web is arranged inlongitudinal rows generally alongr `the grain, the number of which rowsmay be increased successively in accordance with `the increasing widthof the flanges. The nails in each row are staggered at `either side ofthe theoretical'line of row at a small distance from said line as viewedin the transverse direction of the flange, and the nails in every secondrow are displaced at a distance approximately corresponding to half thespace between the rows longitudinally of the flange in relation to thenails in adjacent rows. This arrangement results in several advantages.On the one hand, the geometrically simple and definitely xed placing ofthe nails facilitates a rational construction and manufacture of thebeam and, on the other hand, there are obtained no splitting releasingrows of adjacent nails in any direction. Finally, in nailing accordingto this pattern the ange nails are prevented from being located inoblique rows coinciding with the joints between the boards of the web,independently of the magnitude of the spacing of the nails. This is Veryimportant since otherwise a great number of nails could enter the jointbetween adjacent boards of the web so as to be more or less inoperative,thus resulting in a reduced strength of the beam.

A still further object of the invention is to eiect the nailing by meansof so-called grooved wire nails made of a material of a relatively highyield limit. I have found that nails of this kind have a smallertendency of causing splitting in the wood than ordinary nails of squarecross-section having the same edge dimensions. This is also true, to astill higher extent, in respect of round Wire nails of the same bearingcapacity. The

' grooves also cause that the nails will be reinforced at the fourcorners, thus resulting in an increased rigidness in relation to theconsumption of material. The same remarks apply to the use of materialhaving a high yield limit. A particularly high strength of beamsaccording to the invention may be obtained if the nails used have smalledge dimensions but are as rigid and resistive as possible todeformations when subjected to load perpendicularly to the longitudinaldirection of the nail. In this connection a grooved nail made of a hardmaterial or metal has been found to be particularly advantageous.

Some embodiments of the invention are shown in the accompanying drawingsin which:

Fig. 1 shows an elevation of a portion of a beam according to theinvention.

Fig. 2 is a cross section of this beam on the line II-II in Fig. 1, and

Fig. 3 is a longitudinal section of the beam on the line III-III in Fig.1.

Fig. 4 shows a favourable pattern of nailing in the beam anges accordingto Fig. 1 and Fig. 5 shows, by way of comparison, how one type of ajoint of the beam flanges has hitherto been made in a known manner withexternal joint pieces.

Fig. 6 shows, in elevation, a beam with a broken or angular outlinecomposed of two individually straight beam sections, which are shown indetail in Fig. 7 when taken apart.

Fig. 8 shows on a larger scale a corner joint of such beam portionsafter being assembled, and

Fig. 9 shows a view of one of the beam portions on the line IX-IX inFig. 7.

Fig. 10 is a similar view of the other beam portion, viewed on the lineX-X in Fig. 7.

Fig. 11 is a side View of a piece of beam constructed according to theinvention and having special web stifteners.

Fig. 12 shows the same beam seen in cross section, on the line XII- XIIin Fig. 11.

Fig. 13 shows an elevation, and Fig. 14, a cross section on the lineXIV-XIV in Fig. 13, of a further embodiment of such a beam.

Fig. 15 shows an example of a known joint and Fig. 16 a joint accordingto the invention, between two individually straight assembled beams soas to form a combined beam with great bending strength and with an apexat the joint.

Fig. 17 shows on a larger scale, seen from the side, a joint-piece forthis construction of beam, and

Fig. 18 shows a side view of the whole joint on the same scale. V

Fig. 19 shows a plan view of the joint and Fig. 20 is a cross section ofthe joint according to Fig. 18, viewed along the line XX-XX.

Fig. 21 shows an embodiment illustrating a modified use of the beamcorner construction according to the invention.

Fig. 22 illustrates diagrammatically a view of a tool which may be usedin the nailing operation.

Fig. 23 shows a side view of an embodiment of a purlin arrangement madeaccording to the invention, and

Fig. 24 shows the same arrangement in top plan view.

ln Figs. l `to 3, 1 and 2 indicate the boards of which the web of thebeam is composed and which are arranged in two layers crossing eachother diagonally. When constructing and nailing the beam said boards arelaid close together without any intervening space in order to ensuregreater security against splitting of the web. Flanges 3, 4 and 5, 6respectively, each consisting of at least two layers of laminatedboards, for example a, b, c, mutually glued together are attached to theupper and lower edges of the web of the beam. Each such laminationconsists in its turn of a number of boards jointed longitudinally. Fig.3 shows some oblique joints 6s shaped as hooks for the laminated boardsa, b, c of iiange 6. It should be noted that in Fig. 3 the length ofsaid hook joints are shown on a reduced scale in relation to the widthof the boards.

The end of the beam is preferably tted with vertical strips or laths.These strips as well as the horizontal anges are attached to the web bymeans of nails 9, 1.0 driven in alternately from both sides of the beamin such a way that they entirely penetrate the nearest flange (forexample flange 5) and both layers 1, of the diagonal panelling web, andpartly penetrate mto the other ange (for example flange 6). According toFig. 1 the nails which are driven in from the front of the beam areindicated by the symbol and those nails which are driven in from theback of the beam are indicated by the symbol Fig. 4 illustratesdiagrammatically a favourable pattern of nailing in the flanges. Thetheoretical row lines are indicated at E, F, G and H. The spacing of thenalls driven in from the same side of the ange is indicated .at t. Asshown in Fig. 4 the nails are displaced by the distance from thetheoretical row line on either side of this line in the transversedirection of the flange. The distance between adjacent rows is indicatedat r and it is seen that the displacement between the nails in thelongitudinal direction of the flange in relation to the nails ofadjacent rows is about The arrangements according to the inventionenable the manufacture of beam constructions which with many kinds ofWood, such as Douglas tir, yellow pine etc. would not be possible tomake in any other manner, at least not if the strength of the Wood inthe flanges 1s to be utilized to full extent.

Some of the advantages of me invention will be clear by a comparisonwith Fig. 5 which illustrates a known construction of joining ordinarysolid ange strips or laths to stress transferring anges of great length.

In Fig. 5 21, 22 indicate the two layers of diagonal panelling in theweb of the beam to which anges 23, 24 of solid timber are joined. Theanges 23, 24 are joined in a known way at transverse joints 23s, 24s.External joint-pieces 25, 26 arranged on the outside of these joints,are joined to the ends of the beams to be jointed by means of nails 27,28 and at the same time transmit the forces which the joints 23s and 24sare un- `able lto take.

`the web boards. `web boards, which merely have to transmit thetransversal It `should be lobserved that, in principle, joints 23s, 24scould be made as glued oblique joints in the same way as in the beam inFigs. l to 3, but in practice such a joint does not require anythinglike thesame strength or reliability as when it is` arrangeduaccordingto Figs. l to 3.

The thickness of the anges of the beam is the same in Fig. 5 as in Fig.3 but yet there is required considerably longer and thus alsoheaviernails in the beam according to Fig. 5 than in thebeam according to Fig.3. The n creased length of the nails in Fig. 5 and the resulting increase of the cross-section of the nail causes a considerably increasedweight and cost of the nails required and also an increase `of thesplitting tendency `of the jointed flanges and thus also a reducedstrength of the latter. It should be noted also, that liange jointsaccording to Fig. 3 have a considerably nicer appearance than accordingto Fig. 5.

When using especially hard or brittle timber the splitting resistance asa result of close nailing can, according to a further development offthe invention, be increased in a high degree by special arrangements.Thus according to one form of construction the flanges are made of hardor high grade timber which is generally also characterized by greatstrength and is primarily ensured against splitting by gluing together,as described above, several layers of strips with partially crossinggrains. The web boards, on the other hand, may be made of low-grade orless hard and less strong timber, full advantage being taken of the goodnailing properties of As `a matter of fact the stresses in the forces(shear) in a beam of the present type, have been found to be of a lowermagnitude than the axial and bending stresses in the flanges. As a rulesuch stresses are, at the most, about 1/3 to 1/2 of the stresses in theflanges which are decisive of the dimensions. Several advantages may be`attained by using a combination of lower grade, but softer and toughertimber in the beam web, and highgrade or hard timber which is moreinclined to split in the flanges. The advantages include a lower costfor the assembled beam, increased security against splitting for the webof the beam, and also a slightly lighter beam, and this is attainedwithout the bending strength of the assembled beam being `reduced as inrst line this is determined by the high-grade timber in the flanges. Itshould be observed in this respect that the web boards in the presentcase have to take the relatively low stress right cut to the upper andlower edges of the beam, and in this respect distinguish considerablyfrom., for example, so called glued laminated beams in which thestresses in the entire beam section increase continuously trom thecentral section towards its edges.

The web may also be made of boards of different kind of wood but havingmutually the same thickness. Boards of wood having high strength,particularly a high strength to the local pressure from the nails, areplaced in those portions of the web of the beam (usually in the vicinityof the supports olf the beams) where the transversal forces are greatwhile the remainder of the web of the beam is made of timber having thelower strength. A combination of this kind enables a further increase ofthe strength and a reduction of the costs for the timber required forthe beam, and also a favourable contrast effect, for instance betweentimbers of different colours.

As an example of suitable embodiments according to the invention I maymention beams having flanges of Douglas iir of higher strength qualityand webs of Douglas iir of a lower strength quality, further, beams withflanges of Douglas r and web of spruce, `and also beams with flanges ofDouglas tir, web of Douglas tir in the vicinity of the support of thebeam and web of `spruce in other parts of the beam. Of course, the beamsmayalso be lmade entirely ofthe same kind of timber and also of othertimber classes than those nowmentioned, for instance, of hemlock, yellowpine and other timbers :which can be nailed.

In the web of the beam according to the invention I mayuse short piecesof boards (having a length of for instance 48), which often are obtainedas: a` kind of inferior by-product in the production of ordinary sawtime ber dimensions. In this manner an essential part ofthe ltimber`required for the construction of the beam may be obtained at anextremely low cost which as a rule is not possiblein other types of`supporting wooden constructions of the class now described.

The invention also allows for an arrangementfor connecting two 1beams`of the type in question in a bending resistive manner `at angles to`each other. Such bending resistant beam corners occur in many types ofconstructions, such as frame constructions, arches, beams with broken`outline etc. It is also possible by meansof the invention to producesimply and cheaply larger frame and arched structures `of such a natureon a factory-scale, such `structures being too bulky to transport fullyassembled. They can, however, madein accordance with the invention, betransported as separate, straight and easily transportable parts whichon the building site can be assembled to the frame corners etc. whichhave a good strength to bending stresses and which are requiredfor thestability of the Ibuilt-up supporting units. A remarkable advantage ofthe invention is that the joint at an angle between two parts of thebeam can be carried out on the `building site solely by means ofnailing. Then again the bend-resisting bonds according to the inventioncan be made with the same resistance to bending stresses as both theconnected beam sections individually, and this can be 4made without thedimensions of the corner joints being larger than those of therespective beam sections.

A construction of the kind above indicated is illustrated in Figs. 6 to10 showing -that of the two beams I and'II which are to 'beinterconnected in a manner enabling great resistance to `bendingstresses one beam I at one end is constructed as a stii plate which isresistant to bending stresses in alldirections of the plane of the 'beamand is i-n the form of a quadri-lateral S. This stiff part is formed bythe part of the web of double diagonal panelling 51, 52 of beam I`within the said quadrilateral, also of parts of anges 53, 54 of beam Iwhich are arranged within said quadrilateral, and, iinally, of one ormore special transversals 55 and, if desired, S6 arranged lbetween thesaid iianges 53, 54 and extending in the same direction as the flangesof the second beam II. Then again beam Il is equipped with freelyprotruding forkshaped flanges 59a, 60a which at the building site aremounted so as to embrace the said transversQs 56 and/ or 55 on4bothsides of beam I. Flanges 59a, 60a of 'beam `II are then `connectedto transversal 55 or transversals 55, 56 of beam I together with thediagonal panelling ofthe latter beam. Simultaneously the transversalsfor beam I are also connected to the web of diagonal panelling of thesame beam `by nailing through the anges, transversals and the web of thebeam. This is done with nails the edge-side of which is small, normallyabout J/30 or in extremecases 1/25 of the length of the nail, similarlyto what has been set forth above.

According to Figs. 6 to l() beam I thus consists of a web of diagonalpanel boards 51, 52 and flanges 53, 54 which are joined to the web 'bynailing, and extend along the whole length of the web. The transversal`S5 or transversals 55, 56 are also connected to the web. Of these,transversal 55 should have the same thickness as flanges 53, 54, whereastransversal 56 can be thinner or be omitted yby being substitutedaltogether by flange S9 in Ibeam II. Transversal S5 or transversals 55,56 in Fig. 7 are appropriately only connected with a relatively fewretaining nails to beam section I when the beam sections are beingmanufactured at a factory.

The sections ofthe diagonal panel boards of beam I enclosed within thequadrilateral 53, 55, 54, 56 should preferably be parallel to both therespective diagonals of the quadrilateral. In the remaining part of beamI, however, the direction of the diagonal boards can be adjusted, ifdesired, by separate oblique boards so that both layers of the diagonalpanelling slope or incline equally to the mean longitudinal direction ofthe beam.

Beam II also consists of a web of diagonal panel boards 57, S withllanges 59, 60 and preferably with a lath or strip 61 which forms aterminal or termination for the diagonal web 57, 58. This last mentionedweb terminates along line a-rz in Fig. 6, corresponding to the otheredge of flange 54 in beam I in the assembled structure. The flanges 59and 60 continue with their outer ends in fork-shaped extensions 59a, 60a(Fig. 7). The lengths of these latter are adjusted so that when theforks are disposed along the respective transversals 56 and 55 at beam Ithey reach the outer edge of the outer ange 53 of beam I. It must alsobe taken into consideration in this connection that the mutual freedistance (in the transverse direction of the beam) between flanges ofthe same pair of flanges, for example 60a, shall be so adapted (by asuitable design of the flanges, Fig. 9) that when the flange forks 59a,60a of beam II are disposed along the transversals 55, 56 of beam I nosubstantial clearance will arise lbetween connecting parts of beams Iand II. When beams I and II have thus been placed together nails (thethickness of which, in similarity with the nailing of the flanges,sha-ll be small in relation to the length of the nail) sha1-l be drivenright through ange forks 59a, 60a and into transversals 55, 56 togetherwith the intermediary parts of the diagonal panel webs 51, 52. As a rulethe flange portions 54 and 61 of Fig. 8 should also be interconnectedfor transferring transversal shear which can be effected by connecting aplate of thick plywood or of double diagonal panelling to the parts 54and 61 by means of nails.

It has been found that if the nailing between the flange forks of beamII and the transversals of beam I is carried out approximately asclosely as the nailing between the anges and the web, Ilche connectingarrangement now described lbetween two beam sections which form an anglecan transmit bending moments and normal forces which correspond to fullutilization of the strength in the beam sections outside the cornerjoint.

It is also an object of the invention to make possible the production ofspecially deep, or highly loaded, beams having webs of two layers ofdiagonal panel boards while using thin boards (for example 1") withoutthe web of the :beam acquiring any tendency to buckle laterally. To thispurpose there are arranged on each side of the web of the beam, pairs oflaths or strips which are weak in relation to the ilanges. Said stripsextend mainly parallel or at right angles to the beam flanges. Thestrips which are parallel to the lianges are placed so that they dividethe free height of web between the inner edges of the flanges into twoor more partial heights. Nails are then driven in from both sides of thebeam through the said strips, further right through the web of the beamand,

lfinally, through part of the opposite strip. Opposite strips of thesame pair will now become mutually anchored to each other so as toresist stresses and this is made possible by interconnecting the stripsthrough the beam web by the nails which are driven in from both sides.It is advisable, however, to prevent the nailing from penetrating to theouter edge of an opposite strip. In this manner every pair of oppositestrips hereby will receive a rigidity and strength which is many timesgreater than the rigidity and strength of the individual lath or strip.At the same time the pairs of strips thus mutually inten connected willjoin together both layers of the diagonal panelling of the diagonalpanel beam eifectively. Of both these layers the boards of one layer arenormally exposed to tension stresses throughout their entire length,thereby automatically tending to keep straight, whereas the boards ofthe other layer are exposed to compression stresses which tend to bucklethe last mentioned boards sideways or laterally. It has now been foundthat the coupling of the boards, subjected to compression stresses, tothe boards subjected to` tension stresses, by the medium of, and undercooperation with the interconnected pairs of -strips as described abovegreatly increases the buckling strength of the diagonal panel boards.

According to a modiiication of the invention the laths or strips nailedtogether in pairs are arranged in a direction at approximately rightangles to the beam anges instead of parallel to them. They are placedbetween the inner edges of the beam flanges at a mutually free distancewhich is less than the free height or depth of the beam web (that is theheight between the inner edges of the beam flanges). According to stillanother modification a series of pairs of strips or laths arranged atright angles to the ilanges can alternate with pairs of strips of lathsarranged on certain lengths of the beams and parallel to the flanges. Indoing so I prefer to use the rst-mentioned type when the transversalforce in the beam is relatively great, and the last-mentioned type whenthe said force is small.

Some embodiments of the invention according to the construction nowindicated are shown in Figs. 11-14. The beam shown in Figs. ll and l2comprises a web of diagonal panel boards 61a, 61b having flanges 62, 63.On account of transversal forces in the beam, for example, the panelboards 61a are compressed and the boards 6111 are tensioned in a certainpart of the beam. Laths 64a, 64b are arranged on both sides of the web.They are interconnected in pairs through the web by means of nailing 65of the character described.

Figs. 13 and 14 show another arrangement of the web stiifeners. Herealso 61a, 61b indicate the beam web, and 62, 63 the anges. In this casethe web on the left part of the beam, according to Fig. 13, isreinforced or stittened 'by means of vertical laths 66 intercoupled inpairs on both sides of the web by means of nails 67 of the characterdescribed. The right hand section of the beam is fitted with webstiffeners 68 of the same type as 64a, 64b in Fig. 11. It can be pointedout here that it is also possible, and often appropriate, to combine webstiieners of the type shown in Fig. 11 with the type shown to the leftin Fig. 13 by using the first-mentioned type in beams subjected torelatively small shearing forces and the last mentioned type in beamssubjected to large shearing forces.

The invention also has the object of rendering possible interjoining ofshort beam elements into very long beams at the building place simply bynailing. In this respect the principle of joining ilanges to such beamsis in itself known according to the method shown in Fig. 15, that iswith superimposed joint-pieces of the same strength as the jointedflange 91. Apart from the fact that such a joint looks clumsy it is notpossible either to obtain any great strength as the long, andconsequently also heavy, nails 92 which are required for such a jointare inclined With the close nailing to split the timber in the jointpieces 90 and llanges 91. This applies particularly to heavier loading.These drawbacks are eliminated according to one embodiment of theinvention by interjoining two beams in a bending resisting manner byconnecting their ilanges by means of joint pieces, consisting ofinterglued boards of mainly the same thickness as the boards in theflanges which are to be jointed, the joint pieces being connected to thecorresponding Ibeams by nails of the character described. Said boardsare also so arranged as to always be connected to another board by meansof gluing, whereby there is obtained a high resistance to splitting inthrough-nailing.

An embodiment of this kind is illustrated in Figs. 16-20 which show theinterjoining of -two individually straight beams A and B to a singlebeam having good resistance to bending stresses and forming an apex atthe joint. By

interjoining two beams in this way (which can be done at the buildingplace), several advantages are gained. Firstly, the transport of large'beams is considerably facilitated by only necessitating transportationof individually 4straight: and relatively short beam sections A and B.Secondly, the jointing arrangement also makes it possible to produceroof girders with a relatively slight slope on both sides (thearrangement shown in Figs. 640, on the other hand, is most suitable forjoining beams With a greater angle between the beams). On the otherhand, the necessity of jointing a roof -girder according to Figs. 16-20in its middle section where the stress is greatest naturally placesgreat demands on the 'strength of the joint.

Beam A consists of a web 71 with anges 72, 73, and beam B consists of aweb 74 with flanges 75, 76. Flanges 72 and 75 are jointed by means ofjoint pieces 77 and the tlanges 73, 76 are jointed by means of jointpieces 78. `Beam webs 7l, 74 are jointed by means of special jointpieces 79. Figs. 17 and `18 show details of joint piece 77 seen from theside, and Fig. 19 the same joint piece seen from above, though only forone half of the beam ange (on one `side of the symmetry line of beam80). Each of the anges 72 and 75 which are to be jointed consists, forexample, of three layers of boards 72a, 72b, 72C and 75a, 75h, 75erespectively. The corresponding joint piece 77 likewise consists ofthree layers `of boards 77a, 771;, 77e each of the same thickness as thelayers of boards in the flanges. The joint piece 77, however, can inaddition be provided with still another layer `of boards 77d. This canbe considerably less thick than the other layers of the joint piece. Alllayers a, b, c, d are mutually interglued and thereby block one anotheragainst the risk of splitting in close nailing because of the dissimilarlibres in the layers. When jointing anges with a Ismaller or largernumber of layers of boards than the number shown in Figs. 19 and 20, thenumber of layers in joint piece 77 is reduced or increased to the sameextent as in the flanges.

ln the joint-piece 77 in Fig. 19 the layer '77a can be regarded asjoining material for the layers of boards of ilanges 72a and 75a; thelayer of the joint piece 77b can be regarded as joining material for theflange layers 72b and 75b, and the `layers 77C, 77d can be regarded asjoining material for the ange layers 72C and 75C. The `joint piece 77 isconnected to flanges 72 and 75 by means of nailing, if desired incombination with gluing. The lengths ef, fg, gli, in Fig. 19 areadjusted so as to allow space for the number of nails required totransmit the force in ilange section 72a to ange section 77a of thejoint piece, and to provide on the distance fg a corresponding space fornailing the joint between flange layer 72b and the layer of the jointpiece 77h, etc.

The jointpiece according to the invention has several decided advantagesas compared with the known lapping joint shown in Fig. l5. Thus thelength of the requisite joint nails, and consequently also theirheaviness, is thus considerably reduced. The cost of nailing is herebyreduced, and the risk of splitting is reduced, the strength of the jointthus being increased. Finally, the joining pieces 77, 73 according tothe invention (Figs. 17, l) acquire a much more attractive appearancethan the superimposed joining piece 90 shown in Fig. l5.

Joining pieces according to the invention `can also be used to interjoinshort beam pieces so as to obtain continuous straight beams of greatlength. irrespective of transport dil'culties beams of practicallyunlimited length can be produced by nailing at the building place shortbeams which are factory made but transportable. In such a. case thejoint pieces are made of uniform width in contrast to the joint piecewith broken outline shown in Fig. 17.

The invention also comprises an arrangement for joining the web wheninterjoining two beams to form a single beam, which shows greatresistance to bending stresses. According tothis `arrangement the web'of both beams is provided, at the joint, with laths extending in thelongitudinal direction of the joint. These laths are united withcorresponding laths in the associated beam by means of joining plates ofthick plywood, for example or by double layers of boards mutuallyinterglued temporarily and crossing one another diagonally. Such joiningplates are fixed by nailing to the aforesaid laths and the internalwebs.

An embodiment of this kind is shown in. Figs. 18 and 20. Each beam lweb7l and 74 of the beams the webs of which are to be interjointed consistsof two layers of boards 71a, 71h and 74a, 741) respectively, arrangeddiagonally. Close to the joint each web is terminated by laths 81a, 8117and 82a, S21) respectively, which are provisionally fixed to one anotherand to the respective beam Webs by spaced nailing S3, S4 of thecharacter described. Said laths are finished before the joining, forexample when the beams are made at the factory.

For the joint I use joint plates which if desired can be made of thickplywood though l prefer to make them, for example, of two layers ofdiagonal boards 85a, dn and 851?, 86h, respectively, which areprovisionally glued together. The joining plates are connected at thepoint of assembly to joining laths S1 and S2 of both beams by nailing.This is done with nails of the character described. The intergluingbetween both layers of the diagonal panelling of the joining platescannot be eirpected to hold in the long run because the ber directionsof the glued, relatively thick layers of boards cross one another atright angles, or almost right angles. The gluing in question hastherefore been indicated here as being provisional. Nevertheless thegluing is of great importance since when the joining plates arecarefully stored until they are ready for assembly the gluing causesboth layers of boards to interlock in the close nailing made onassembling by means of the plates. As a result of this interlockingeffect such close nailing can be carried out without any risk ofsplitting of the individual boards of the joining plates. lt is: truethat this gluing loses its strength after some time, but the joiningplate is nevertheless found to retain its anti-splitting capacity. Thisappears to be due to the wood of the plate adjusting itself plasticallyto the nailing in time, but such adjustment cannot take place alreadywhenthe momentary assembling nailing is made.

`Fig. 2l shows an embodiment of the invention in which the`quadrilateral S according to Fig. 7 is arranged at the joint between alattice-girder 9i) and a beam 91. In the beam 99 the web is substitutedby separate diagonals or laths `92, 93 connected to the wooden anges `ofthe beam. The `quadrilateral S is made of two layers of diagonal boardswith nailing substantially as described with reference to Figs. 6 to l8.Beam 91 may or may not have any diagonal panel web between its Woodenanges.

lIn many cases it is not-economical to elfect the nailing accordingtothe invention manually but by means of a tool, for instance by meansof a percussion tool operated by compressed air or by other means. Aspecial tool hasbeen developed to this purpose and is showndiagrammatically in longitudinal section in Fig. 22. It cornprises apercussion tool 94 of ordinary type having a cylindrical pin or bolt 95which 4is operated by compressed air in `known manner so as to perform apercussion movement. The pin 95 has an enlarged head or ange 96 servingas an abutment for a sleeve v97 of rubber, plastic or other elastic butnot too soft material. The sleeve 97 is extended slightly at 97a beyondthe free end 98 or the bolt 95which is adapted to engagethe head of thevnail 99 so `as to drive the latter into the wooden pieces 100, forinstance the ang'e strips of the beam described, `on operating thepercussion `bolt 95. One function of the rubber sleeve 97 is to guidethe bolt 95 so as to prevent it from sliding `off the head ofthe nail 99during the percussion operation. Another remarkable effect of the rubbersleeve 97 is due to its extension 97a which for instance has a length ofabout 10 mm. When the tool is caused to engage the head of the nail andthe compressed air is supplied the said extension 97a will be compressedaccording as the percussion tool is acting to drive the head of the nailinto the wood so that this sleeve will protect the wood around the headof the nail from being damaged by the tool, yet Without preventing saidhead from being driven in close to the wooden surface.

The invention also includes a favourable construction of a purlin orjoist of a roof with the use of nailing of the character described.Figs. 23 and 24 illustrate an embodiment of this kind. In these gures110, 111 indicate two roof beams or trusses, for instance constructed inaccordance with any of the embodiments now described. On the top of saidtrusses the purlins which carry the roofing (boards, sheet metal etc.)extend transversely to the longitudinal direction of trusses. In manycases the purlins now in use are made in the form of separate beams ofsolid timber or lumber having sub stantially the same length as `thespace between the trusses, and freely supported by said trusses, but thepurlins may also be made continuous, for instance by causing the purlinsto overlap one another on the trusses. However, this last mentionedconstruction necessitates the use of purlin beams having a greaterlength than the space between the trusses and the consequence of this isthat rather great timber lengths are required for the purlins. It isoften diicult to obtain timber of suiiciently great lengths if the spacebetween the trusses is great and in any case the costs will increasewith increasing lengths of the timber. This disadvantage is very serioussince for other reasons it is desired to arrange the trusses at so greata distance as possible from one another so as to reduce the number oftrusses for a given roof area. On the other hand continuous purlins orjoists have the advantage of providing a more favourable distribution ofthe moments and a reduced bending than freely supported purlins having aspan equal to the space between the trusses.

Now, according to the invention there is provided an arrangement whichenables obtaining a favourable distribution of moments simultaneouslywith the great economy of material inherent with the continuous purlins,yet without necessitating great length of the timber or lumber, andwhich, in addition, enables an adjustment of the cross-sectional area ofthe purlin to the bending moment. A combination of these advantagesresults in a very remarkable economy of material in relation to theordinary itype of purlins which are laid freely between the trusses. Thesaving of the volume of material is theoretically about 50%, and sinceit is possible to utilize rather short lengths of timber the costs perunit of volume will be low.

As illustrated in Figs. 23 and 24 these advantages are gained, accordingto the invention, by using wooden purlin elements 112 of shorter lengththan the distance between the trusses or beams 110, 111, such shortelements being lengthened by a pair of double wooden pieces 113, 114.The single wood piece 112 is arranged in the central part of the eldbetween the supporting trusses 110, 111 and the double wooden pieces113, 114 are arranged on the top of the supporting trusses. Each pair ofwooden pieces 113, 114 is adapted to receive the respective end of thepurlin element 112 in a fork-like manner between the individual woodenpieces of each pair as shown in Fig. 24, so that the end of the element112 will overlap the ends of the pieces 113, 114. To this purpose thewooden pieces in each pair are spaced at a distance corresponding to thewidth of the intermediary element 112. If desired, spacers 11S may bearranged between the wooden pieces 113, 114 and fixed thereto by meansof nails. The purlin element 112 is 12 joined to the double woodenpieces 113, 114 by nailing 116 which is to be dimensioned so as Ito bearthe moment stresses and thus render the joint resistive to bendingstresses. The nailing joints 116 should preferably be placed at such adistance from the supporting means or 111, that thebending moments atthe place of the joint will be as small as possible. As shown at 11611,the nailing for every second purlin 112, can be made in a more simplemanner so as to bear the shear stresses only. In this case the jointswill be made as articulations. lt is easily 4seen that this arrangementrenders it possible to adjust the distance of the joints 116, 116a fromthe support on the trusses 110, 111 and to adjust the distribution oflthe moments on and between said supports so as to utilize the strengthof the wooden pieces 112-114 in an extremely advantageous manner.

It a tendency of splitting should arise at the places of nailing 116,116er metal sheets may be interposed between the overlapping woodenparts and the nails are driven through these sheets and into the woodenparts.

The pairs of wooden pieces 113, 114 may be attached to the trusses 110,111 by means of oblique nailing, for instance.

At the ends of the roof the free ends of the purlin elements 112 mayrest on suitable supports without any lengthening arrangement 113, 114,if desired.

What I claim is:

l. A wooden beam construction comprising a web of at least two layers ofboards disposed in each layer in edge to edge relation to each other andwith their lengths in angular relation to the lengths of the boards inthe other layer, said lengths in each layer extending diagonally withrespect to the length of the beam, flange members of wood disposed withthe lengths thereof generally parallel to the grain extending along therespective opposite lengthwise edge portions of the beam at oppositefaces of said web, each llange member comprising at least two boards inlaminated face-to-face relation to each other and to said web at theadjacent face of the web, and nails driven through the boards of therespective ange members into said web, said nails being disposed in aplurality of rows lengthwise of said ange members and staggered in eachrow with respect to the general line of the grain of the wood of saidflange members, said nails being disposed in groups along said rows withthe nails that are disposed in adjacent rows staggered in relation toeach other along respective lines transverse to said rows, said linesbeing spaced along said rows, the spacing in each group between thenails staggered along the transverse line of said group beingapproximately V2 the spacing between said adjacent rows of nails.

2. A wooden beam construction as defined in claim 1 in which all of thenails of a given group are at the same side of the respective lines ofthe rows, the nails of two adjacent groups along the ange member beingdisposed at opposite sides of the respective lines of the rows.

3. A wooden beam construction as delined in claim l which compriseswooden strips disposed in face-to-face relation to the respective facesof said web and extending with their lengths in registering relation toeach other over a portion of the extent of said web between said iiangemembers and generally parallel to said ange members so as to divide thespace between said ange members into at least two portions extendinglongitudinally of the beam.

4. A wooden beam construction as dened in claim 3 in which additionalstrips in face-to-face relation to the respective faces of said webextend transversely of said ange members so as to divide the spacebetween said flange members into portions spaced longitudinally alongthe beam.

(References on following page) References Cited in the le of this patentUNITED STATES PATENTS -Nutt Dec. 22, 1936 Prosnack Mar. 11, 1941 LankSept. 18, 1945 Winkel Nov. 27, 1945 Sahlherg Dec. 4, 1945 'Thomas Dec.30, 1947 14 Shannon Feb. 13, 1951 Brosenius Aug. 26, 1952 FOREIGNPATENTS Sweden Aug. 17, 1943 Sweden Aug. 15, 1944 Sweden Sept. 5, 1944Sweden July 10, 1945 Sweden Mar. 10, 1949

